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# sizing of pump, anybody ?

Jeff Elston Member Posts:

**289** Can you be more specific please?

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14Still hoping someone can tell me how to size a pump`s feet of head properly

it-on Walt. Let`s have your particulars!

Dave

289> Can you be more specific please?

>

>

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14Guy`s go down the list of new messages and you`ll see feet of head (posted by O`bee) that was my second posting on this subject. I really appreciate any help .

289How many GPM?

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289> Guy`s go down the list of new messages and you`ll

> see feet of head (posted by O`bee) that was my

> second posting on this subject. I really

> appreciate any help .

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289We need more info

I would usually start with BTUs and such

If you had something else in mind please do tell!

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1413 gallons per minute , (have 130000 btu/hr worth of convectores , with the longest loop at 258'

Ken was pretty specific,,, so did you re-check your numbers?

Dave

14I`m having trouble with one part of the equation , it`s the13 which is my GPM , with the1.75 next to it , I don`t know wether to time`s it by the 13 or divide it , square root etc.....

What are you looking at? Where do you get 1.75? Forget all that Sq.rt. stuff, like Ken said just give us the length of the longest circuit, and I thought you said you needed to move 13 GPM right?

Dave

14I got that 1.75 from my head loss equation formula in my I=B=R guide it say`s head loss or h = (equivelent length divided by 100)times (a),which in my book relates to 0.274, times 13, which is my gpm, you know what never mind , how would you find the feet of head of a pump if you know the equivalent length and the gpm

289So if we assume a 20* delta the GPM will 13

The pipe size should 1 1/2 copper

and at a length of 285' you will have a pressure drop of 5 FT

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14Dave the longest circuit is 258' and your right I`m using 13gpm but i`m not just looking for the answer, but I`d like to know how you came up with it , for the next time I run into this situation. thank`s

1 GPM will transport 10,000 BTU, so your load is 130MBH so you will need 1.25" pipe to begin with. Now your longest run is 258ft.+50% fitting allowance which is 387Ft. What size pipe is this longest run?

Dave

289Well I learned by reading Dan's books and by doing it on the job

Please see attached

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1,291Your longest run is 258' but it probably doesn't carry the whole 13 GPM flow, correct?

If so, you need to identify what the GPM load is in that zone. Probably more like 4-5GPM or 40-50,000 BTU? That's going effect your calculation considerably.

14the 258' allready includes the 50% allowance for fittings,the pipe size for that zone (which is one zone of 4 ) is 3/4"

14yes

that`s Dan,,, I read his books too,,,did I miss something? Not trying to be smart, but please correct me if I`m wrong.

Dave

14the gpm for that zone is 4 , as the pipe is 3/4" an it is a 3/4" taco zone valve the water must pass through

1,291I figured your head based on a flow rate that will give you a 20* temp drop and assumed a load of 40KBTU in that zone. This also assumes that the zone in question is actually the zone with the highest head in your system. Some may be shorter in length but have a greater number of restrictions but that's a whole 'nuther discussion. For your particular setup, the assumptions I made should all appear on the printout. In addition to those seen I figured 20 90* ells and a couple ball valves. How much baseboard do you actually have, or are we dealing with something else?

still need to move 13GPM, or do you have separate circs? (hope so)

Dave

14yes Dave I need to move 13 gpm when all 4 taco zone valves are open

14thanks Steve , it is the longest run out of all the loop`s and it is a 20 degree temp drop, sorry I didn`t mention that

I was better at computers, seems like Steve`s got-it for ya!

Dave

14thank`s , for every-ones help

592Not very clear but this what I think is going on. 4 different loops which as a group, carry 130,000 btuh of heat. Rule of thumb, based on 20 delta t, 1 gpm will release 10,000 btu's of heat. You need to calculate the loop with the highest head loss - probablly the longest loop with the most radiation. Calculate the head losses in each loop. Take the highest value, add to that a number for fittings, and loss through the boiler system.

You mentioned zone valves. Unless they are full port, they will have a cv value. Based on the flow rate, this value is used to calculate the head loss / press drop through the valve. The higher the flow for any given cv, the higher the head loss. Although they are probably minimal in your case, they are still there.

See attached tables - they may help you understand the process better. The spread sheet is fun, you put in what ever values you want for flow and CV and it calculates the resulting head loss / press drop. I've also included an article on equivalent fittings by Siggy. You've got everyting here except the pump curves.

Good Luck

1,291That shows only what that particular zone requires for flow and develops for head.

Here's another one showing what you need for total flow and the circ required. Zones 2-4 are figured at 180' of length with 70' of BB in each circuit along with the same 20 elbows.

It'd be interesting to know how many feet of BB you actually have in each zone. 40,000 btu's is about all you can carry in 3/4 tube without having some serious amounts of heat emitters and getting your temp drop up in the 30* range.

1,291Yours truly has very limited computer skills. That's how easy Siggy's Hydronic design software makes those kinds of calcs.

I`ll have to remember that, (typing with one finger and all), will take a better look at the software, Thanks Again!

Dave

and your input is invaluable (I enjoy your posts), but to make a long story short where Walt`s concerned, do you not think we covered enough?

BTW- Those are great charts!

Dave

592Yes it was covered enough Dave, but I thought having the charts would help him, or anyone else, the next time around. Don't always have a computer on at your disposal.

I didn't see the other posts while I was typing mine. Sorry for all the extra repeat verbage .. glad you like the charts.

Glenn

don`t get me wrong, I really do enjoy your posts, and I have learned too, I look forward to alot of your contact OK?

Take Care!

Ya know,,you can always Email me.

Dave

592Sorry I protected the whole sheet. I meant to protect the answer cells so you can't accidently foul up the formula. This spreadsheet version will work.

Sorry